In recent years, it has become common practice to enhance the sensual effects of various kinds of music by modulating the intensity of various light sources located in the listening area in response to the sound level of the music.
One method for accomplishing this result uses acoustical pick up devices to change the sound into electrical impulses which then control various types of power control devices that in turn vary the level of power applied to a light source. This approach has the disadvantage of allowing any sound, even an undesired noise, to vary the light output unless sophisticated circuitry designed to provide noise immunity or to respond to signals only above a predetermined intensity level is utilized.
In addition, in setting up such a system to provide a sound/light program it is necessary to provide a source of music such as a conventional analog electromechanical sound reproduction device, for example a phonograph or tape recorder, or as an alternative, a live performance by one or more musicians. Signals broadcast from commercial broadcasting stations may of course also be used, but then it is generally not possible to have control of the program, which is based on the discretion of the broadcaster. A further difficulty is that the volume level of the sound may not be adjusted without having an effect on the intensity of the light source.
Another method uses the analog electrical audio signal output of a sound reproduction means to control the power control device that in turn varies the power level to the light source. While this avoids the problem of extraneous noises influencing light intensity, the other disadvantages mentioned above still remain.